Humans are thought to have evolved from a mixture of environmental and humanbased selective pressures. Changes in resource availability and , forced some populations of primates to become [ Sele as they traveled across long distances, freeing hands for tools and complex tasks. Later, a. fleeing from b. hunting c. domesticating large animals required communication, while [Select ] a.outsmarting b. cooperating with v ^ rival groups of humans c. competing selected further for intelligence. .